Source Count: 15 | Weighted Score: 38 | Source Confidence: [4/5] | Primary Tier: 2 | Last Updated: March 11, 2026
Keywords: infrasound, low-frequency sound, sub-bass, 18.98 Hz, Vic Tandy, standing wave, resonance, Helmholtz resonator, piezoelectric, sound pressure level, bioacoustics, elephant communication, whale song, seismic signal, atmospheric infrasound, CTBTO, nuclear test detection, wind turbine syndrome, brown note, ghost frequency, haunt, anomalous experience, vibration, acoustic weapon, LRAD
Category Tags: quantum physics and mechanics
Cross-References: J_1_04 — Ancient Acoustics · J_1_06 — 110 Hz Resonance · O_1_03 — Geomagnetic Anomalies · ZF_4_04 — Underwater Acoustics · K_1_01 — Quantum Consciousness · O_1_09 — Persinger Tectonic Strain Theory · ZB_2_01 — Animal Cognition

QUICK SUMMARY

Infrasound — sound below the conventional human hearing threshold of ~20 Hz — is a pervasive physical phenomenon generated by natural sources (wind, ocean waves, volcanic eruptions, earthquakes, thunderstorms, animal vocalizations) and artificial sources (machinery, wind turbines, explosions, traffic), whose study has revealed both practical applications (nuclear test detection via the CTBTO's International Monitoring System, elephant and whale communication research) and contentious claims about biological and psychological effects on humans, including reports of anxiety, unease, visual disturbances, and "haunting" sensations attributed to standing waves near 18–19 Hz (the resonant frequency of the human eyeball, per Vic Tandy's 1998 investigation). The physics of infrasound are well-established — long wavelengths (17+ meters at 20 Hz) enable propagation over enormous distances with minimal atmospheric attenuation, making infrasound a tool for monitoring volcanic eruptions, meteorite entries, and clandestine nuclear tests — while its biological effects remain an active and contested area of research, sitting at the intersection of acoustics, physiology, psychology, and anomalistics.

1. VERIFIED CLAIMS (Tier 1 — Peer-Reviewed / Experimentally Confirmed)

1.1 Physics of Infrasound

• Infrasound occupies the frequency range below ~20 Hz; at these frequencies, wavelengths exceed 17 meters (at 20 Hz in air at 20°C, λ ≈ 17.15 m) and increase to hundreds of meters at 1 Hz
• Low-frequency sound experiences significantly less atmospheric absorption than audible frequencies — attenuation at 1 Hz is approximately 10⁻⁷ dB/km compared to ~5 dB/km at 10 kHz (Bass et al. 1995, JASA)
• This allows infrasound to propagate over thousands of kilometers — the eruption of Krakatoa (1883) produced infrasonic waves that circled the globe seven times, detected by barometers worldwide (Strachey 1888)
• Infrasound below ~1 Hz is typically classified as microbaroms (ocean-generated) and atmospheric gravity waves; these are continuously present in Earth's atmosphere and detectable by modern sensor networks

1.2 CTBTO International Monitoring System

• The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) operates a global network of 60 infrasound monitoring stations (IMS) designed to detect atmospheric nuclear explosions — these stations can detect events producing >0.01 Pa pressure perturbations at distances of thousands of kilometers
• The IMS detected the Chelyabinsk meteor (February 15, 2013, ~500 kt equivalent) at stations across the globe, providing independent energy estimates (Brown et al. 2013, Nature)
• Volcanic monitoring: the 2022 Hunga Tonga-Hunga Ha'apai eruption produced the most powerful atmospheric infrasound event recorded by modern instruments — pressure waves circled the Earth multiple times and were detected by barometers and infrasound arrays worldwide (Wright et al. 2022, Science)

1.3 Animal Infrasound Communication

• Elephants (Loxodonta africana, Elephas maximus) produce vocalizations at 14–24 Hz (fundamental frequency) at sound pressure levels up to 117 dB SPL, detectable by other elephants at distances of 2–4 km under favorable conditions; Payne et al. (1986, Behavioral Ecology and Sociobiology) first documented this
• Baleen whales — particularly blue whales (Balaenoptera musculus) and fin whales (B. physalus) — produce calls at 15–20 Hz (fin whale "20 Hz pulse") that propagate across ocean basins; the SOFAR channel enables detection at distances exceeding 1,000 km
• Cassowaries (Casuarius spp.) produce infrasonic boom calls (~23 Hz) — among the lowest-frequency bird vocalizations known (Mack & Jones 2003)

1.4 Natural and Industrial Sources

• Ocean microbaroms: continuous infrasound at ~0.1–0.5 Hz generated by opposing ocean wave systems (Longuet-Higgins 1950) — this forms the dominant background infrasound signal globally
• Wind turbines: produce infrasound at blade-passing frequency (typically 0.5–4 Hz depending on rotor speed); levels at 300–500 m are typically 50–75 dB SPL at frequencies below 5 Hz — below audibility thresholds at these frequencies (Bolin et al. 2011, JASA)

2. CREDIBLE CLAIMS (Tier 2 — Academic / Debated but Supported)

2.1 Physiological Effects at High Intensities

• At high sound pressure levels (>120 dB SPL), infrasound can produce measurable physiological responses: chest wall vibration, respiratory rhythm modulation, mild nausea, and a sensation of pressure (Møller & Pedersen 2004, JASA)
• The resonant frequency of the thorax is approximately 50–80 Hz, while the abdominal cavity resonates at ~4–8 Hz — exposure to high-intensity infrasound near these frequencies can cause discomfort and visceral vibration
• Controlled studies by Leventhall (2003) for DEFRA (UK) concluded that infrasound at levels encountered in occupational and environmental settings (below 90 dB SPL at frequencies <20 Hz) is unlikely to cause direct health effects, but acknowledged that "annoyance" and "stress" responses are possible at levels well below those causing physical harm, particularly when combined with audible low-frequency noise

2.2 Vic Tandy's 18.98 Hz Finding

• Vic Tandy (1998, Journal of the Society for Psychical Research) investigated reports of "ghostly" experiences in a laboratory at Coventry University — feelings of dread, cold sensations, and peripheral visual disturbances; he discovered a standing wave at 18.98 Hz produced by an extraction fan, at sufficient amplitude to cause visual disturbance by vibrating the human eyeball (the eye's resonant frequency is approximately 18–19 Hz, per Gavrilov 1963)
• When the fan was modified, the anomalous experiences ceased — Tandy proposed this as a partial explanation for "haunting" reports in buildings with infrasound-generating mechanical systems
• Follow-up work (Tandy 2000) measured infrasound in reportedly "haunted" locations — the Edinburgh Vaults — and found 18–19 Hz infrasound correlating with locations where visitors reported anomalous experiences
• This work is peer-reviewed but based on small sample sizes and specific case studies rather than large-scale controlled trials

2.3 Psychological Experiments

• French et al. (2009) at Goldsmiths, University of London conducted a controlled experiment exposing participants to 18.98 Hz infrasound in an "experience room" — results showed a small but statistically significant increase in reported "unusual experiences" (tingling, nervousness, unease) in the infrasound condition vs. control, but the effect size was small
• Crichton et al. (2014) demonstrated that expectations about infrasound significantly influence symptom reporting — participants told they were being exposed to infrasound reported significantly more symptoms regardless of whether infrasound was actually present (nocebo effect), complicating all self-report-based infrasound research

3. SPECULATIVE CLAIMS (Tier 3 — Possible but Unverified)

3.1 Ancient Architectural Infrasound

• Researchers have proposed that megalithic structures (e.g., Newgrange, Ħal-Saflieni Hypogeum, the Great Pyramid's subterranean chamber) may have been designed to generate or amplify infrasonic standing waves during ritual use — resonance measurements at some sites have detected infrasonic modes, but whether these were intentional design features or incidental acoustic properties is unknown
• This connects to documented research on the 110 Hz resonance at Ħal-Saflieni (Cook et al. 2008; → J_1_06) — while 110 Hz is audible, the principle of deliberate acoustic design in ancient architecture has parallels in the infrasonic range

3.2 Geological Infrasound and Anomalous Experiences

• Persinger's tectonic strain theory (→ O_1_09) proposes that seismic stress in fault zones generates electromagnetic and infrasonic emissions that can affect human neurophysiology — producing sensations interpreted as paranormal phenomena, UFO sightings, or religious experiences
• While tectonic processes do generate infrasound and electromagnetic emissions (both well-documented), the hypothesized causal chain from geological infrasound → specific perceptual distortions → paranormal interpretations remains speculative

3.3 The "Brown Note"

• The "brown note" — a hypothetical infrasonic frequency (~7 Hz) that allegedly causes involuntary bowel evacuation — has been tested and not confirmed by controlled experiments; the TV program MythBusters (2004) found no effect at frequencies from 5–50 Hz at SPLs up to 120 dB; Leventhall (2003) notes no credible evidence for this claim in the acoustic literature
• While not entirely impossible at extremely high SPLs (>150 dB, approaching pain/injury thresholds), such levels would cause multiple physiological harms beyond any hypothetical bowel effect

4. DUBIOUS CLAIMS (Tier 4 — No Credible Source / Contradicted by Evidence)

4.1 Wind Turbine Syndrome

• Claims that infrasound from wind turbines causes "wind turbine syndrome" (headaches, insomnia, tinnitus, anxiety) have been extensively reviewed — the Australian NHMRC (2015), Health Canada (2014), and Oregon Health Authority (2013) systematic reviews found no consistent evidence that infrasound at levels produced by modern wind turbines causes direct health effects
• DEBUNKED Measured infrasound from wind turbines at typical residential distances (300–1,000 m) is well below audibility thresholds at relevant frequencies — typically 10–30 dB below perception threshold (Evans et al. 2013, Acoustics Australia)
• Reported symptoms correlate with annoyance from audible turbine noise (aerodynamic swish), visual impact, and nocebo effects (Crichton et al. 2014) rather than infrasonic exposure

4.2 Infrasonic Weapons Causing Mass Incapacitation

• Claims of "infrasonic weapons" capable of remotely incapacitating populations — frequently circulated in popular and conspiracy literature — are unsupported by physics: the enormous wavelengths at infrasonic frequencies make beam-forming extremely difficult (antenna arrays would need to be hundreds of meters across); atmospheric absorption is low but spreading losses over distance are substantial; and the energy required to produce physiologically significant SPLs (>130 dB) at distance is prohibitive
• While LRAD (Long Range Acoustic Device) and similar directed-sound systems exist, they operate at audible frequencies (2–3 kHz) where beam-forming is practical — these are not infrasonic devices despite frequent conflation in popular media

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COUNTER-ARGUMENTS & CRITICISMS

No significant counter-arguments exist in the scholarly literature for the core claims presented here. The topic of Infrasound Physics Biological Effects represents established knowledge within quantum physics and theoretical physics with no active scholarly dispute over the fundamental claims presented in this document.

BIBLIOGRAPHY

1. Bass, H.E. et al | 1995 | "Atmospheric Absorption of Sound: Further Developments" | Journal of the Acoustical Society of America | ∅ | 97.1::680–683 | ∅ | ∅ | doi:10.1121/1.412989 | ∅ | ∅ | ∅
2. Brown, P.G. et al | 2013 | "A 500-Kiloton Airburst over Chelyabinsk and an Enhanced Hazard from Small Impactors" | Nature | ∅ | 503.7475::238–241 | ∅ | ∅ | doi:10.1038/nature12741 | ∅ | ∅ | ∅
3. Payne, K.B., Langbauer, W.R.; Thomas, E.M | 1986 | "Infrasonic Calls of the Asian Elephant (Elephas maximus)" | Behavioral Ecology and Sociobiology | ∅ | 18.4::297–301 | ∅ | ∅ | doi:10.1007/BF00300007 | ∅ | ∅ | ∅
4. Møller, H.; Pedersen, C.S | 2004 | "Hearing at Low and Infrasonic Frequencies" | Noise & Health | ∅ | 6.23::37–57 | ∅ | ∅ | ∅ | ∅ | ∅ | ∅
5. Tandy, V.; Lawrence, T.R | 1998 | "The Ghost in the Machine" | Journal of the Society for Psychical Research | ∅ | 62.851::360–364 | ∅ | ∅ | ∅ | ∅ | ∅ | ∅
6. Tandy, V | 2000 | "Something in the Cellar" | Journal of the Society for Psychical Research | ∅ | 64.860::129–141 | ∅ | ∅ | ∅ | ∅ | ∅ | ∅
7. Leventhall, G | 2003 | "A Review of Published Research on Low Frequency Noise and its Effects" | ∅ | ∅ | ∅ | DEFRA Report | ∅ | ∅ | ∅ | ∅ | ∅
8. French, C.C. et al | 2009 | "The 'Haunt' Project: An Attempt to Build a 'Haunted' Room by Manipulating Complex Electromagnetic Fields and Infrasound" | Cortex | ∅ | 45.5::619–629 | ∅ | ∅ | doi:10.1016/j.cortex.2007.10.011 | ∅ | ∅ | ∅
9. Crichton, F. et al | 2014 | "Can Expectations Produce Symptoms from Infrasound Associated with Wind Turbines?" | Health Psychology | ∅ | 33.4::360–364 | ∅ | ∅ | doi:10.1037/a0031760 | ∅ | ∅ | ∅
10. Wright, C.J. et al | 2022 | "Surface-to-Space Atmospheric Waves from Hunga Tonga–Hunga Ha'apai Eruption" | Nature | ∅ | 609::741–746 | ∅ | ∅ | doi:10.1038/s41586-022-05012-5 | ∅ | ∅ | ∅
11. Bolin, K. et al | 2011 | "Infrasound and Low Frequency Noise from Wind Turbines: Exposure and Health Effects" | Environmental Research Letters | ∅ | 6.3::035103 | ∅ | ∅ | doi:10.1088/1748-9326/6/3/035103 | ∅ | ∅ | ∅
12. Longuet-Higgins, M.S | 1950 | "A Theory of the Origin of Microseisms" | Philosophical Transactions of the Royal Society A | ∅ | 243.857::1–35 | ∅ | ∅ | doi:10.1098/rsta.1950.0012 | ∅ | ∅ | ∅
13. Cook, I.A. et al | 2008 | "Ancient Architectural Acoustic Resonance Patterns and Regional Brain Activity" | Time and Mind | ∅ | 1.1::95–104 | ∅ | ∅ | doi:10.2752/175169608783489099 | ∅ | ∅ | ∅
14. Mack, A.L.; Jones, J. . )120[1062:LVBCCS]2.0.CO; 2 | 2003 | "Low-Frequency Vocalizations by Cassowaries (Casuarius spp.)" | The Auk | ∅ | 120.4::1062–1068 | ∅ | ∅ | doi:10.1642/0004-8038(2003 | ∅ | ∅ | ∅
15. Strachey, R | 1888 | "On the Air Waves and Sounds Caused by the Eruption of Krakatoa in August 1883" | Proceedings of the Royal Society of London | ∅ | 45::50–56 | ∅ | ∅ | ∅ | ∅ | ∅ | ∅

CROSS-REFERENCE INDEX

Created from cross-cutting keyword analysis — "infrasound" appears in 9 documents across 7 sections. Last Updated: March 11, 2026